Electromagnetic indicator



Aug. 9, 1927. 1,638,614

F. e. BREWSTER ELECTROMAGNETIC INDICATQR Filed Feb. 25. 1922 latented Aug. 9, 1927.

UNITED STATES FRANK G. BREWSTER, 01? WHITE RIVER JUNCTION, VERMONT.

ELECTROMAGNETIC mmoarron.

Application fl1ed February 25, 1922. Serial No. 539,209.

This invention relates to an electromag netic indicator and has foran important object thereof the provision of, a structure whereby an armature associated with a plu- 5 rality of electro-magnets may be accurately positioned to correspond to energization of certain of these magnets.

A further object of the invention is to provide a structure extending the effective range'of the magnets, so that the armature may be shifted through a suitable range thereby. f

A still further object of the invention is to provide a device of this character which may be comparatively cheaply constructed, which is simple in its operation, dependable and durable in service and a general improvement in the art.

Other objects and advantages of the invention will become apparent throughout the course of the following description.

In the accompanying drawings wherein for the purpose of illustration is shown a preferred embodiment of my invention and wherein like reference characters designate like parts throughout Figure 1 is a transverse sectional view taken through the indicator;

Figure 2 is a section taken on' the line 22 of Figure 1;

Figure 3 is a diagram 'showing the elecrical connections and operation of the various parts of the device;

Figure 4 is an end elevation of the armature member.

Referring now more particularly to the drawings, the numeral 28 designates an indicator casing having arranged therein a plurality of eleetro-magnets 29, the magnets 29 being arranged upon an arc and each having one terminal connected by a wire 30 with a segment 20 and the other'terminal 31 thereof grounded. The are upon which the magnets 29 are arranged-has for its con-- ter the axis of a shaft 32 provided upon its upperend with an indicating pointer 33 operating over a dial 34 provided with suitable indicia 35. 'To this shaft is secured an armature member 36 of peculiar constrnction, as clearly disclosed in Figure 1. .This armature member is curved upon an arc of less magnitude than the are upon which the electro magnets 29 are arranged, the radius of curvature being of less length than t e dis ase b tw en the test r of the armature and the axis of the shaft 32 so that the curvature is such that the ends 37 of the armature are spaced from the magnet are a distance greater than the central portion thereof. This central portion, as clearly disclosed in Figure 4, is of greater size than the end portions of the armature. The purpose of the peculiar curvature and shaping of the armature will hereinafter appear.

With an indicator of this character, I preferably employ a switch comprising a disk 21 rotating about an axis 16 and having a brush 23 coacting with a plurality of segment contacts 20. This brush is preferably of such size that it bridges the space between adjacent contacts in passin from one to the other thereof, so that at th1s time, both contacts are electrically connected to the disk. The disk may receive current through a brush 26.

In the use of my device, with a switch of I the character described, the dial casting 28 is arranged upon the dash and one terminal of each of the magnets thereof rounded, as hereinbefore indicated. The p unger brush 26 is then electrically connected by a wire 38 with a suitable source of current 39, the opposite terminal of the source of current being in series with a switch 10 and with the ground. Upon the switch 40 being closed, the current passes through the brush 26' to the head 21, through the brush 23 of the head 21 to a contact 20, energizing the same and causing the magnet thereof to attract the armature. It is here pointed out that the ends of the armature 36 will be arranged so as to be spaced from the magnets 29 a sufficient distance that they just come within the magnetic field thereof. Accordingly, if a magnet be energized which lies at a pointcorresponding to an end of this armature member, this end will be attracted causing a swinging movement of the armature and this swinging movement will continue until the central portion of the armature is opposed to the energized magnet, due to the fact that the attraction of the magnet increases. It is here pointed out that thisstructure permits the use of magnets} of relati'vely low strength, eliminating the necessity of providing a ma neti'ze'd armature such as has been commo y utilized in these devices as there is no necessity for increasi g the fie d f the m g t y u h e n By this arrangement the field of a magnet may be enlarged to any desired extent by simply increasing the ength of the arms 36 of the armature 36, and where heretofore the magnetic field would only extend through an effective distance of say threequarters of an inch, the same may be extended indefinitely.

From the fore oing it is believed to be obvious that an eectroinagnetic signal constructed in accordance with my invention is particularly Well adapted for the purpose for which it is intended by reason of the fact that the use of costly magnetized armatures is eliminated and the structure of the signal simplified and improved. It will furthermore be obvious that the structure as hereinbefore set forth is capable of some change and modification Without materially departing from the spirit of my invention and I accordingly do not limit myself to such specific structure except as hereinafter claimed. I

I claim: a

In a device of the type described, a movable member, a pivoted shaft bearing the movable member, electro-magnets arranged upon an arc with the axis of the shaft as a center and an armature carried by said shaft in spaced relation to the shaft, said armature being curved in the same general direction as the are upon which the eleetro-magnets are arranged and having a radius of less length than the distance between the attached portion of the armature and the axis of said shaft, said armature bein of such length that when the attached portion thereof is aligned with one of said electro-magnets, the end portions thereof are extended between adjacent electro-magnets and the shaft, said armature uniformly decreasing in size from its center to the ends thereof.

In testimony whereof I hereunto affix my signature.

FRANK G. BREIVSTER 

